1. FIELD OF THE INVENTION
This invention relates to impact devices, and more particularly to an impact device for use in machines such as presses utilized in marking, punching, stamping, forming, riveting and other related operations.
2. DESCRIPTION OF THE PRIOR ART
To accomplish marking, punching, stamping, forming, riveting and other related operations, it is customary to economize on the use of energy and size of equipment required by storing a given quantity of energy through elastic means, such as a compressed spring, and subsequently releasing the elastic means to impart the necessary force to a workpiece.
Machines of this type have included a tubular shaped spindle in which a hammer and tool are axially movable. The hammer is displaced relative to the spindle thereby compressing a tension spring which at a given moment is allowed to expand and drive the hammer onto the head of the tool.
There are various manners in which the spring expansion can be achieved. For example, in French Pat. No. 1161913, the structure consists of a circumferential groove in the hammer into which a plurality of balls are placed. An enlarged section of the spindle is constructed which will allow these balls to move radially, thereby freeing the hammer. A socket is interposed circumferentially between the hammer and spindle, encircling the hammer and holding the balls within the hammer groove. The relative displacement of the hammer and spindle is achieved through the socket pressing on the balls within the hammer groove. When the hammer groove is in line with the enlarged section within the spindle, they are forced out of the hammer groove, thereby releasing the hammer to strike the tool, releasing the energy in the compressed spring. There are also other springs coaxial with the hammer and socket to allow return of the balls to the hammer groove after impact.
Although such devices have been extensively used, they are not without deficiencies. Because of the relatively large number of components, the devices are complex and difficult to assemble. Further, the force must be transmitted through a series of components, thereby limiting the ultimate impact force. And, the large number of components results in a relatively expensive device.